As a substituted alkylamine having a condensed heterocyclic ring, useful for the above usage, there are known 1-(2-benzothiazolyl)alkylamines represented by the following formula: ##STR4##
For synthesis thereof, a process is known which uses a condensation reaction between 2-aminothiophenol derivative and amino acid-N-carboxy anhydride (see JP-A-8-325235).
However, for example, (RS)-1-(6-fluoro-2-benzothiazolyl)ethylamine produced by the above conventional process is low (34%) in yield; moreover, the 2-aminothiophenol derivative used as a raw material is unstable in air and emits an odor and, therefore, has been difficult to handle industrially.
Thus, there has been proposed no industrial process capable of synthesizing a 1-(2-benzothiazolyl)alkylamine from a 2-aminothiophenol derivative at a high yield with easy handling of the derivative.
In view of such a situation of the prior art, the present invention has been completed with an aim of providing an industrial process capable of synthesizing a 1-(2-benzothiazolyl)alkylamine or its salt from a 2-aminothiophenol derivative at a high yield with easy handling of the derivative.